# Questions tagged [optics]

Optics is the study of light, and its interaction with matter. It includes topics such as imaging systems, fiber optics, lasers, quantum optics, and more.

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### Material that Increases Angle of Incoming Light

Snell's law states that light refracts when entering a substance and refracts back to its original angle upon exit. This is shown in the diagram below from this webpage. I was wondering if there are ...
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### Convergence of rays at focal plane after reflection from concave mirror

My teacher taught us that rays parallel to each other(but not necessarily parallel to the principal axis), after reflection from a concave mirror,get converged at a sharp point somewhere on the focal ...
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### Moving laser beam passing over stationary circular opening

I am in need of help with the following situation. I appreciate any insight. Imagine a circular laser beam of diameter d1 moving at velocity v passing over a stationary circular opening of diameter d2 ...
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### Dipole term in light-matter interaction

I have a question regarding the description of the term “dipole” in light-matter interactions. If I understand it correctly, there are 3 different things that one can declare as a dipole during light-...
1 vote
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### Calculating mirror size for a teleprompter

I'm trying to calculate the required size of a mirror for a teleprompter application. The goal is to use the smallest possible mirror while still capturing the full image. It's a straightforward setup,...
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### Diffraction when the wavefront is not parallel to the plane

I am studying Feynman's chapter on the origin of the index of the refractive index (see this link). If I am not mistaken, what he does is to prove that when a wave enters a medium (modelled as a ...
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### Field propagation in metamaterial based optical fibres?

We have an optical fibre having HMM cladding ( $\mu=1$ and have a permittivity tensor with one component different in sign than others) and a core having permittivity equal to one. How will light ...
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### Calculating focal length for wide angle conversion lens [closed]

How do you calculate the focal length for a wide-angle conversion lens, say with a factor of 0.7, that would convert a 50 mm lens to a 35 mm lens, e.g. for photography. Such a lens should be a concave ...
1 vote
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### Snell's law in materials having negative permittivity only?

We have reverse Snell's law in negative index materials (having negative permittivity and permeability). If we have a material with only negative permittivity , then can we also have reverse Snell's ...
1 vote
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### According to Huygens' Princple, what happens to secondary wavelets when the sphere encircling the secondary source intersects a mirror?

A parallel light beam travelling towards a convex mirror. Wavefronts are shown with dotted lines. Consider the wavefront at the instant when the rays are just about to touch the mirror. Say, we have ...
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### What is the relation between the Faraday effect and the Zeeman effect?

The Faraday Effect basically says that certain materials under a magnetic field have different indexes of refraction for right and circular polarized light. Linear light which is a superposition of ...
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### When building a fiber optic interferometer what methods are used to reduce microphonic effects?

When building a fiber optic interferometer what methods are used to reduce microphonic effects? I'm familiar with a few methods such as: enclosing the interferometer under a sound dampening cover, ...
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### How do I calculate the absorption of single layers of a multilayer stack using the electric field in each layer?

I'm trying to calculate the absorbance of individual layers using the transfer matrix method but I'm stuck on how to do it. The code I am using can give the total absorbance of the system, and the ...
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### "Extraordinary polarization" in a birefringent optical medium

In Nonlinear Optics by R. W. Boyd, I came across the following sentences about light polarization in an uniaxial birefringent medium: Light polarized perpendicular to the plane containing the ...
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### Confusion regarding phase

As far as I know about phase if the phase difference between two waves is positive, the former is leading..and the latter is lagging. Then why has D J Grifith stated this? If the phase of the magnetic ...
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### Huygens' principle and the laws of reflection/refraction

As I understand the Huygens principle, all points on the wavefront are sources of secondary spherical wavelets and the tangent to these wavelets will form new wavefront. This is used to prove the ...
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### Is there a good quantum explanation of refraction? [duplicate]

I'm aware of the classical explanation of refraction which deals with light being a wave that gets "slowed" down while passing from a medium to another. One problem that I have with this ...
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### At which wavelengths do photons behave like X-ray?

Hard X-rays of wavelengths of about an angstrom are very different than regular lights in a way that they can’t be reflected or refracted, which means their refractive index is always close to 1 ...
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### Directionality of laser light in vacuum [duplicate]

It is well-known that laser light is directional because of coherence from stimulated emission. This means that the light is emitted ONLY in the direction of propagation, and not in any type of ...
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### Eye Floaters Optics

Eye floaters are these annoying objects floating in someones eye, usually seen by someone experiencing them as squiggly lines and dots buzzing around, either dark or partially transparent (I ...
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### Michelson interferometer but with 1 arm (Part 2)

I designed a setup similar to Michelson Interferometer but with one mirror only. So, there is an angle between the 2 rays to the detector: In order to understand the result on screen, I used (Zemax/...
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### Absorption and emission spectrum terminology

Hi everyone recently i was looking for laser crystals and since I am an autodidact i was confused by the terminology and units of the optics domain. And specialy by the absorption and emission ...
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### Can a collimated laser have curved wavefronts?

I know that a plane wave's collimation is affected by the curvature of its wavefronts. But since laser beam is composed of many plane waves, does it still apply ? Although there is always some ...
1 vote
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### How is light interference explained with photons?

In the classical model of light as an EM wave, interference is a trivial consequence of the linearity of the wave equation. Now, if we model light as collections of photons, how is light interference ...
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### Can an optical medium be lossless and dispersive?

Occasionally, I come across the phrase "lossless dispersive linear optical medium". How can such a medium be possible mathematically? I mean the real and imaginary parts of the electric ...
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### Modified two slit diffraction experiment

I thought up a slight modification to the classic two-slit experiment that would be fun to try, but I am certain that I am not the only person to consider it, and would like to know if it has already ...
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### Why is vertically polarized light preferentially refracted at the surface and horizontally polarized light preferentially reflected?

I was reading OpenStax Physics on the topic of polarisation and Brewster's angle but there was no clear explanation as to why vertically polarised light generally refracts while horizontally polarised ...
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### Would the use of LIPC's for Lasers avoid eye damage for bystanders?

Laser Induced Plasma Channels (LIPC) can create a tunnel of plasma in the air for a brief moment (milliseconds). But the formation of a LIPC is a process and not something instantaneous when it comes ...
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### What does the optical Hamiltonian mean?

So I was trying to demonstrate Snell's law with Hamilton's equations, and when I got the Hamiltonian: $$H = -\sqrt{n^2-p_{1}^2-p_{2}^2}.$$ I had a question about what this Hamiltonian indicates. I ...
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### Exit Pupil, Objective Aperture, Magnification, and Brightness

Why is it that for two pairs of binoculars, with equal aperture, the one with smaller magnification has larger exit pupil and results in brighter images? If I understand correctly, the aperture ...
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### Using multiple sources in Zemax mixed mode

In Ansys Zemax OpticStudio [I'm using 2023 R1.00 Pro (11)] sequential mode, the Multi-Configuration Editor can be used to make multiple paths for rays to trace through after the rays depart from a ...
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### Can the laser light, in principle, take any wavelength in the EM spectrum?

Can the laser light, in principle, take any wavelength in the EM spectrum? I don't think there is what prevent this in principle, right?
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### Assessing the quality of wavefront correction in adaptive optics systems: the case of single and multiple radiation sources

Generalized diagram of an adaptive optical system is as follows: Wavefront from the observation object passes through the atmosphere and is distorted. It is then reflected from the deformable mirror ...
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### When light hits an interface between air and glass, different refraction results ensue if it is a prism or a window. Why? [duplicate]

If light hits a window it bends and comes out parallel, but if it hits a prism it breaks into a rainbow. How does it know the shape of the glass it is entering?
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### Average polarization of photons and lasers

Sunlight is made up of photons polarized in many directions, so it is derived that sunlight has a 50% chance of passing through a polarizing filter at any angle. My question is, if you know 50% of ...
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### Is there an actual difference between the scattering and absorption/emission of a photon?

Consider a photon incident upon a atom. Dependent on the electronic makeup of the atom, the frequency of the light, and/or group velocity of incident photon, we might see: Various elastic/inelastic ...
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